Supporters of Republican presidential candidate Donald Trump, left, face off with protesters after a rally on the campus of the University of Illinois-Chicago was cancelled due to security concerns Friday, March 11, 2016, in Chicago. (AP Photo/Charles Rex Arbogast)

WASHINGTON – In a normal U.S. presidential election, the focus around now would be on the front-running candidates pivoting toward the centre and refining their message for a general-election audience.

Not this year.

With five states preparing to vote in crucial primaries, the Sunday talk shows were dominated by much darker discussions: in one interview a sighing, head-shaking Marco Rubio was musing about death — both figurative and literal.

He expressed fear someone might be killed at a rally. And he suggested the rise of Donald Trump had injected a toxicity into the body politic that, if not purged soon, could wind up killing American democracy itself.

“We’re going to lose our republic,” Rubio told CNN. “All the rules that once governed our discourse have been blown away. And we’re headed in a very dangerous direction.”

He said seeing angry clashes at a Donald Trump rally reminded him of third-world scenes.

When the host asked whether he feared someone might die at one of these events, he replied: “That’s what it feels like. It feels like we’re reaching a point now in America where everyone hates each other.”

The immediate catalyst for all this angst was protesters filling up a Trump event the other night in Chicago. When organizers realized what was going on, they cancelled the rally, which led to confrontations.

Protesters have become increasingly invasive in trying to hijack the events of a candidate they accuse of being a hate-mongering xenophobe.

Initially the protests were mainly outside. In New Hampshire, someone stood outside an arena in a Ku Klux Klan-style bedsheet. Later in South Carolina, there was a scatological-themed protest outside with brown logos and slogans urging Republicans to, “Dump Trump.” The protests have occasionally moved inside, and become more disruptive.

The PA systems at some events have warned Trump supporters: It’s a First Amendment right to protest. Please don’t hit anyone. Just chant Trump’s name, and security will come escort them out.

But Trump himself is accused of muddying that message of anti-violence.

His rivals illustrated that in an attack ad featuring clips of Trump saying: “Punch him in the face…knock the crap out of him…carried out on a stretcher…I will pay for the legal fees.”

The campaign has indeed mused about paying the fees for a supporter who sucker-punched a protester, and defended a Trump campaign manager accused of bullying a reporter while she asked a question, allegedly grabbing her arm hard enough to leave a bruise.

Trump says he’s the one being aggrieved.

He accused Bernie Sanders supporters of trying to shut down his rallies, and issued a warning Sunday on Twitter: “Be careful Bernie, or my supporters will go to yours!”

He complained of a double-standard.

“If (my supporters) ever went to Bernie’s rallies and did the same thing… you would be so angry with me,” Trump said in an interview on CBS’s “Face The Nation.”

“If people went to their rallies, and disrupted their rallies, like my rallies are disrupted, the press would stick up for them.”

He dismissed the idea he’s whipping up crowd anger. “I’m constantly saying to the police, ‘Don’t hurt them.”‘ And he pointed out that he’d cancelled his rally over fear of violence, which he said was the responsible thing to do: “I don’t condone violence.”

He appeared momentarily in danger himself this weekend.

The Secret Service rushed onstage to protect him from an approaching protester — whom Trump dismissed as probably a supporter of the Islamic State.

Former Ronald Reagan speechwriter Peggy Noonan, now a political analyst at CBS, spread the blame around. She levelled some at protesters. Some of it, she said, belongs with a candidate she called cavalier and immature.

Rubio said plenty of people will need to examine their conscience after this election — including a news media offering wall-to-wall coverage of the ratings-grabbing Trump while denying it to others.

There he was again Sunday, all over the TV.

One of his several interviews included a surreal moment: A show host pleaded with the candidate to change. Jake Tapper on CNN said he’d covered many protests at political events over the years, but the difference is that other presidential hopefuls would try soothing the mob — not encourage it.

“I would just ask, as a fellow American, if you could consider whether or not dialing down the temperature… might be a healthier thing — both for your campaign and for the nation.”

A set of crucial primaries arrives his week. Florida, Ohio, North Carolina, Illinois and Missouri vote Tuesday in the first winner-takes-all-delegates contests. The results could help determine whether Trump goes into the summer convention with enough delegates to secure a first-ballot win.

He leads the Republican polls in four of the five states, trailing only in Ohio to the governor of Ohio.

Trump replied to Tapper: “(CNN) should report it right. We’ve had no injuries at my events — with thousands of people.”